Below is the comparison chart that explains the differences between Pro and Standard.  Standard is not just Pro minus the TT.  But, if you have TT, then you could probably try out the Standard and upgrade to Pro later if you hit the limited presets or layers. Standard 6 is priced so that if you later upgrade to Pro-6 the prices for those are similar to if you had just bought Pro-6 from the beginning (so trying Standard first could be a benefit to you, if you find it meets your needs).